triple beam balance

[toppkatt]

Hoping someone has a triple beam balance capable of weighing 690G in 0.1G increments.
Reason: Sporter Air Rifle has a trigger pull weight of 1.5 pounds (or 680.4G) per CMP rule book. Try as I might there are NO commercial products that can measure this exact weight. The NRA 'official trigger weight set' sold by Brownells comes with a 500G base (which is slightly more than 1 pound (~454G)). The next smaller weight to add to base is 1/2 pound. Now if the base was 1 pound that would be fine but since it's not you can only measure 1 pound and approximately 9.5 Oz. so above the 1.5 pound (1 pound 8 Oz or 680.4G) needed to measure the trigger in sporter. I machined a mass that Is close but I need to verify the additional mass I made brings it up to the correct mass needed.
I don't want some 'jury rigged' looking item on the line during gear check. That might just provide those interested in protesting when their gear fails a reason, at least more so than a device that at least seems 'correct'. Plus, I want this to BE ACCURATE, not just look it, that's why I'm looking for this balance and willing to take the time to verify my weight.
Thanks

 

[Magnumite]

The link wouldn’t copy paste. Try this on Amazon if you want to have it on hand. Otherwise try talking to a high school science teacher.

Visit the Yescom Store
3.9 3.9 out of 5 stars 121 Reviews

Triple Beam Mechanical Balance Scale Weight Set 2610g 0.1g Lab Analytical Weight​

 

[smdub]

I have a MyWeigh triple beam scale and an Atlantic Scale Company F class cal weight set. (whos last cal date was in 2000 but it doesn't change enough over time for me to care.) 500+100+50+20+10+10=690. I can hit it on the nose.

 

[toppkatt]

The link wouldn’t copy paste. Try this on Amazon if you want to have it on hand. Otherwise try talking to a high school science teacher.

Visit the Yescom Store
3.9 3.9 out of 5 stars 121 Reviews

Triple Beam Mechanical Balance Scale Weight Set 2610g 0.1g Lab Analytical Weight​

Thanks, but I'm trying to avoid spending any money on an item I'll likely use once. :-)

 

[Magnumite]

 

[atblis]

nvm

 

[mauser58]

I have never heard of weighing with a scale. I use a trigger pull gauge to adjust Lbs. of pull on adjustable triggers.

 

[BFMIN]

Me neither.
this might help you.

{The 5} Best Trigger Pull Gauges in 2023 [February Tested]

Looking for the best trigger pull gauges in 2023? Our team of experts spent 56 hours to pick top 5 rated models & brands for you

thegunzone.com

 

[mauser58]

I have two wheelers I use when building rifles and installing adjustable trigger

 

[toppkatt]

CUSTOM GUNSMITHING, INC. NRA OFFICIAL UNIVERSAL TRIGGER WEIGHT SYSTEM | Brownells

Check out the CUSTOM GUNSMITHING, INC. available Online at Brownells Today and many more Gauges & Measuring Tools products are available in our Tools & Cleaning Department.

www.brownells.com

From CMP 3P Rule Book: (colored, bold and italics text added by me)
'
'4.2.3 Trigger Weight
The minimum trigger pull for a Sporter air rifle is 1.5 pounds (680.4 grams). The cocked
trigger must be capable of lifting a weight of 1.5 pounds. Trigger pull weights must be
checked with a fixed, hanging weight. When triggers are tested, the test weight must be
lifted so that its entire weight is clear of its support surface. Note: Merely shifting the weight
on the support surface is not sufficient; the entire trigger weight must be lifted so that it is
suspended above the support surface. If a rifle does not lift the weight on the first attempt,
a maximum of three total attempts may be made. The weight must be lifted on at least one
of the three attempts. The athlete or athlete’s coach may make one of the three attempts. If
a trigger is weighed before a competition as part of an equipment inspection and it does not
pass, the trigger may be adjusted and resubmitted for additional trigger weight tests. Match
Officials may check trigger pull weights before a competition (during equipment control),
during a competition or immediately after a competition. If a trigger is tested and fails to lift
a 1.5-pound trigger weight during or after a competition, all scores fired with that rifle up to
that time in that event (course of fire) must be disqualified. Electronic trigger testing devices
may be used to check rifles, but any decisions regarding whether the trigger passes must
be confirmed with a 1.5-pound trigger weight'

According to my calculations the masses (weights) I machined are less than 1 grain (64 mg) less than the 680.4 G required. Hence the need to weigh the weights I made...with the triple beam balance (to physically verify my calculations).

 

[BFMIN]

Ask them where you can obtain such a device at reasonable cost?

 

[toppkatt]

Ask them where you can obtain such a device at reasonable cost?

They couldn't answer that. I tried.
Even theirs looked 'jury rigged'.
Guess I have too much pride in my work to look that way when finished.

 

[toppkatt]

All's well that ends well and this has ended up well. I was able to get together with forum member smdub and use his triple beam balance. I'm satisfied with the weights I have and their accuracy & precision.
Thanks again smdub! Nice meeting you.

 

[Magnumite]

cudos to smdub…

 

[chale127]

Dumb question(s)...
1-Do they even check this?
2-If so, how do they do it?

 

[toppkatt]

Dumb question(s)...
1-Do they even check this?
2-If so, how do they do it?

Yes during gear check though MANY matches do not require a gear check it is still in the published rules. It can be before the match or after. Typically (at least in my limited experience) it's before. That way the trigger may be adjusted to conform to the published standards. If a judge is concerned something has taken place at sometime during the match (altering the trigger weight after gear check) the trigger could be tested again. If the trigger is found to be in violation all the results shot with that rifle are voided. Also, the shooter or coach is allowed to test the trigger pull weight for one of the three allowed trials.
The only accepted mechanism to test the trigger pull weight is by raising a fixed hanging weight from a platform via the trigger. Electronic or mechanical gauges are NOT acceptable to determine trigger pull weight. The barrel should be perpendicular to the platform surface and the rifle raised slowly. There are no established criteria stating the rate the rifle is raised only that it is raised slowly and uniformly (i.e. no 'at a rate of XXX inches per minute'). To test the rifle it must be unloaded, cocked and the safety disengaged.
When I shoot in the N-SSA skirmishes they often do random checks on the line before and after shooting with the same criteria (should the rifle fail the trigger pull weight the results of that match for that rifle/shooter are voided).

 

[smdub]

Great meeting and chatting w/ you toppkatt!

A picture is probably worth 1000 words here. Snap a pic of your rig hung from a rifle.

 

[toppkatt]

I'll try to get a picture posted (good idea). Also, lest one think trigger pull weight is the only factor checked in gear check, the size (diameter and length) of the kneeling roll, width of the sling, whether shoes are higher than the ankle and if the sole isn't flat, if trousers are too tight (judgement call, no defined criteria in rule book), weight of the rifle, even the width of the belt in the trousers (my team was gigged once for this because our belts were 1mm too wide(!) and they were regulation Navy web belts).

 

[BFMIN]

^^^
This is why I quit shooting competitively years back.
Its all rubbish & not marginally relevant to the shooting.
I once got gigged for the COLOR of my regulation sling. It wasn't anything outrageous or anything it just "looked a little too dark", It was the last straw.

 

[chilipeppermaniac]

^^^
This is why I quit shooting competitively years back.
Its all rubbish & not marginally relevant to the shooting.
I once got gigged for the COLOR of my regulation sling. It wasn't anything outrageous or anything it just "looked a little too dark", It was the last straw.

When I was in HS, I had 2 friends who rode horses, One did show jumping where rider and horse get judged, the other races Steeplechase. The steeplechaser said he used to show jump too but the subjectivity taints the results. In steeplechase, first across the line wins.